Heavy duty buffing device



June 22, 1965 A. L. ZANOW HEAVY DUTY BUFFING DEVICE Original Filed Nov.30, 1962 I u p i for railway car sliding sill construction.

United States Patent 3,190,458 HEAVY DUTY BUFFENG DEVICE Andrey L.Zanow, Cleveland, Ohio, assignor to National Castings Company,(Ileveiand, Ohio, a corporation of Ohio Continuation of application Ser.No. 241,285, Nov. 30, 1962. This application Mar. 1, 1965, Ser. No.438,461 9 Claims. (Cl. 213-43) This invention relates to a hydraulicshock absorbing device adapted for use with heavy vehicles such asrailway cars. The invention is concerned particularly with butfingdevices which are currently regarded as having unusually long cushioningstrokes, e.g., two feet or more, and have recoil damping mechanismadapting such devices This application is a continuation of UnitedStates application, Serial No. 241,285, filed November 30, 1962, and nowabandoned.

An important object of the invention is to provide longtravel,heavy-duty buffing devices in which the radial support of an assemblymovable within the device comprising its piston and the piston rodtherefor is obtained primarily at two longitudinally spaced points tothereby achieve substantial economies in manufacturing without sacrificeof performance or maintenance economy.

A further object is to provide buffing devices in accordance with theforegoing object which are inherently free of oil leakage.

Still another object is to provide a butting device which is of openconstruction between the piston and the seal for the piston rod thereofwhile also providing efiective recoil snubbing.

Broadly speaking, this invention resides in a hydraulic butter forrailway vehicles, or the like, comprising a cylinder having an open rearend and a front end substantially enclosed by a cylinder head or wall; apiston reciprocable within the cylinder with a piston rod thereforextending rearwardly through and beyond the open cylinder end; acylinder extension, preferably of smaller internal diameter than thecylinder, normally joining with the cylinder adjacent its open end, andextending rearwardly in coaxial relation with both the cylinder and therod; an annular sealing medium surrounding the piston rod and securedthereto in fixed longitudinal relationship to tightly engage the fullcircumferenceof the inner surface of the cylinder extension and becarried lengthwise thereof by the rod; a reservoir normally constructedaround the cylinder and the head thereof and connected with the cylinderfor the exchange of liquid for receiving and discharging liquid inaccordance with decreases and increases in the volume of the cylinderand the space between the rear of the piston and the sealing medium.Finally, the buffer includes appropriate duct system for the transfer ofliquid between the space rearward of the piston and the liquid storageregion provided by the cylinder and the reservoir since increases anddecreases in the volume of this space occur in the operation of thebuffer.

The invention further includes structure for returning liquid leaking bya portion of the piston rod seal to a region contiguous with theinterior of the cylinder.

In the drawing with respect to which this invention is described below:

FIG. 1 is a central longitudinal cross section in elevation of ahydraulic butter in accordance with the invention in its fully extendedor open condition.

FIG. 2 is a fragmentary central longitudinal cross section in elevationof the buffer of FIG. 1 in its contracted or closed condition.

FIG. 3 is a fragmentary enlargement of an intermediate "ice portion ofFIG. 1 including the junction of the cylinder with the cylinderextension.

FIG. 4 is a fragmentary enlargement of a portion of FIG. 1 illustratingthe rear portion of a cylinder extension of the buffer and the sealingmedium carried by the piston rod.

FIG. 5 is a fragmentary transverse cross section in elevation of theforward end portion of a butter incorporating a modified cylinder headand relationship thereof with the cylinder.

FIG. 1 illustrates a buffer 3 substantially in its entirety adapted asto general arrangement to fit in a pocket resembling the conventionaldraft gear pocket of a railway vehicle. Normally, the terminal abutmentpieces of the butter 4 and 5 will engage stops (not shown) of draft gearpocket structure fixed within a vehicle, and also be engaged by stops orabutments (not shown) of an oscillating device, e.g., the buff-and-draftcolumn of so-called sliding sill arrangements. As shown, the abutmentpiece 5 is attached to a piston rod 7 by a structure permitting limitedswivel action. The piece 5- is of generally annular conformationadapting it as a spring seat for a pair of springs 8 and 9 which standin a state of initial compression between the piece 5 and a flange 10bolted to the rear end of a housing 11.

Other basic components of the buffer are a cylinder 12 supportedinternally of the housing 11, a piston 14 reciprocable lengthwise of thecylinder, a tubular cylinder extension 15 extending rearwardly from theopen rear end of the cylinder 12 in coaxial relation with the cylinderand the piston rod 7. A front edge portion of the extension 15 extendsinside and longitudinally overlaps a rear end edge portion of thecylinder 12 as shown most plainly in FIG. 3. The flange 10 is fixed tothe extension 15 by means, such as the weld 16 shown. The flange isbolted to the housing to hold the extension 15 in the longitudinallyoverlapping and coaxial relation with the cylinder 12. In this mannerthe rear end of the cylinder is positioned with respect to the housing.The front end of the cylinder seats against a head 18 along an outerradial flange 19 of the head. Radial registry of the cylinder with thehead is established along a drum surface 21 of the head 18 adjacent theflange 19. The drum surface extends internally of the forward end of thecylinder. The housing 11 comprises a plurality of lugs 22 in concentricarrangement with the axis of the cylinder, e.g., three lugs spaced 126degrees apart to engage a concentric boss 23 fitting within the lugs.The front face of the head 18 abuts against the rear surfaces of thelugs. In this manner, the cylinder 12 and the head 18 are fixedlypositioned relative to the housing 11.

The head 18 has a further function of supporting a metering tube 25'fixed thereto in coaxial arrangement with the head, the cylinder and anelongate bore or opening 26 extending through the assembly comprisingthe piston 14 and the piston rod 7. As shown, the opening extends fromthe front face of the piston rearwardly for a length at least equal tothat of the portion of the metering tube extending rearwardly of thehead 18. The front end portion of the opening 26 closely conforms to theouter periphery of the tube 25 to restrict the flow of liquid therepastand to thus enhance the hydraulic resistance of the buffer to externalcompression loads. The metering tube has minute apertures 28 ofpredetermined aggregate area and pattern through its tubular wall whichermit transfer of liquid between the region Within the cylindersurrounding the tube and the interior of the tube during both closingand return strokes of the piston and the piston rod assembly.

The piston rod is maintained in concentric or coaxial relation with theextension 15 by the concentric relation of the piston and the cylinder,and also by a sealing mechanism 31 carried on the piston rod in fixedlongitudinal relation therewith. As shown'in FIG; 4, the outer sur-.

face of the piston rod 7 is undercut to provide shoulders 32" and33jbetween whichannular sealing means, such as the sealing mechanism 31, is retained at 'a fixed point along 'the rod length. The mechanism 31seals the space disposed forwardly from the mechanism within thecylinder extension-and the cylinder from the atomosphcre or spacerearward ly adjacent to the mechanism; The sealing mechanism, as shown,comprises a rigid ring 350i a material such as metal, a plurality ofsmallcompre-ssion the buffer to be fully expanded, as shown in FIG; 1,

an initial increase in pressure to a high level is experienced withinthe cylinder 12 frontwardly of the piston as soon springs 36back-stopped by the-ring 35 and pushing against as buffer closurecommences Liquid is forcedthrough the holes 28 of the metering tube asthe piston moves through its pressure working stroke. Most of the liquidtravels frontw-ard'ly within the tube into the central and radialopenings-63 and 62m,v respectively, of the boss 4 '23, and a radialpassageway 6311 of the housing, into the reservoir" region '64 definedby the outer wall of the housing-1 1 and the cylinder 12; .The region64, in addition to a reservesupply of oil, alsoscont-ains a pocket ofair. Some of the liquid forced out of the cylinder 'by the frontwardmoving "piston travels :rearwardly through the tube into the opening 26and thence through the piston passageway 59 through the opened checkvalve comprisingthe washer 62 and into the space 42; This space israpidly increasing in volume as the piston moves for- Proceeding to; animportant feature of the invention,

structure is now to bede-scribed-whichfeeds any liquid leaking by thefront portion "of the seal, i.e., the ring 35, back'into the internalregions of the piston and cylinder assembly. It is characteristic of theoperation of the wardly. Eventually, a conditionof the buffer may be 7reached asv shownin'v-FlGrZ-wherein the piston is abutting the'cylinderhead 18;

In executing-a return stroke that of FIG.'2, a very 'great reduction inpressure within buffer hereindescribed that the space 42, disposed in aradial direction between the outer surface of the piston rod and theinner surface 43 of the extension15, and in a longitudinal directionbetween the sealing mechanism and the rear face-of the'piston 44 todefineabufier chamher back of the piston, confinesliquid at the maximumIn order to return liquid'which leaks past the ring 35, the ring isprovided, e.g., with a plurality of radial circumferentially spacedopenings 45 extending from'a circumferential groove 44 a in the outersurface of-the ring to a liquid gathering circumferential groove 44b inthe undercut surface of the pistonr-od. The'groove 44b intersects with apressure-relief passageway, i.e., a radial bore 46, contiguous with arear terminal portion 47 of reduced diameter of the opening 26. Portion47 of the opening forms a shoulder 48 with an adjacent'portion of the.opening of larger diameter suitable as a seat for .a ball 49 cooperatingtherewith and together forming a check valve. A pin 51 trapped in aradial bore therefor by'the ring 35 maintains the ball 47 in thevicinity of the shoulder 48.

Inspecting now the enlarged view of the portion of the-cylinder occursasisoo'n' asvthe piston moves away frorn'the cylinder head 18. Astheliquid in the reservoir is'subject to pressure by an'air cushionconfined therein, liquid immediately starts touflow from :the reservoirthrough the: head'ls, and through the apertured wall of the meteringtube .to'fill thecylinder 'in front of the piston. However, as soon asthe piston starts to move rearwardly, pressure increases in the space 42because of entrapment therein as the washer ,62 closes off the rearterminus of the passageway 59.; Restraint in the escape of liquidfrom'the. space 42.is the major impediment to return ofthe piston andpiston rod assembly. The liquid is metered from the space 42 intothepassageway 59 through a small clearance 66 0f the washer 62 with theinner surface of the cylinder 12. This clearance is contiguous with oneor more small grooves 67 in the rear face of the piston body 54 adjacentthe front face of the washer 62. Such agroove along with the clearance66 constitute a small orifice or channel through which liquid passesfromthe space 42 to the passageway 59 and then into the opening 26.

the piston is shown to comprise a body- 54 secured to the,

front end of the piston rod 7 by a. plurality. of bolts 55., The bolts55 also secure a retaining flange 56 providi ng a shoulder 57 spacedfrom the front face of the body for loose .support of a washer 58functioning with the front terminus of a passageway 59 as a check valvealong the front'face of the piston. The passageway 59 also branchesrearward to form arear terminus along the rear face of the body 54.The-undercut peripheral area at the front end of the rod 7 for receivingthe piston provides a On accountof thehigh pressure developed in thespace 42 during the return stroke, some'leakage of liquid past the ring35 is inevitable.Asthe liquidpressure is quite low in the fopening26'at'this instant, the ball 49 unseats from theshoulder 48 to return'anyliquid passing the ring S'Sdand through the duct.46 to the interior ofthe piston ro 1:

FIG. 5 illustrates in'transverse section the front portion of a modifiedbuffer wherein s'ome'p'arts are identical to thoseillustrated in FIG, 1and other analogous parts or features are given "the same numeral exceptthat the letter a .is added In'cont'rast withthe embodiment of 7 FIG. 1wherein asealin'g ring 66 is provided. in the peripheral surface 21 ofthe head 18 to join the head and the' cylinderwall in sealedrelationship, the head 18a of shoulder 61 spaced from the rear end ofthe body 'portion 54 permittingfreedom of movement of a washer 62';vfunctioning in cooperation with'the rear terminus of the passageway 59as a check valve restricting, at one stage FIGJS and the cylinder 12iare constructed with cooperating' surfaces including a surface 21a andthe radially exte'ndingtrear-facing surface '19s of the flange 19a ofthe headto position and support the front end of the "cylinyder' in themanner accomplished in the embodiment of of operation, the flow ofliquid from the space 42 through the passageway into the central opening26. Underother conditions of operation, the washer 5 8 restricts theflow of liquid from the region in the cylinder surrounding the meteringtube, 25 into the opening 26-01 the space,

FIG. 1.' The essential difference between the two embodiments is thatthecircumferential expansion of the cylinder 12 awayfrom the "surface'21tzoccurs at the pressures under which buffers in accordance with thisinvention In operation, the buffer of FIGS. to 4 is of the re-s Icoilless type characterized by substantial hydraulic re-, J

sistance, i.e., return stroke resistance pressure, tothe but ferexpanding action of the springs 8 and 9..Aesuming are operated, tweenopposed axially extending surfaces of the head and the cylinder'whichmeters liquid from the cylinder into theireservoir. That "is 'to say,the end portion of the. cylinder 12 overlapping 'the;surface 21a expandsinla radial directionawayfrom the surface to permit the passage ofliquid into ia.;plura lity of radially extending grooves from acondition such as Such expansion provides 7 clearance be- 68 in theflange 19a, i.e., in the surface 19s of the flange 19a and thence intothe reservoir region 64. The grooves 68 enable the flange 19a to be usedas a seat for axially positioning the cylinder 12. Provision of thegrooves 68 is optional when the casing is designed for the deformationentailed in forcing a clearance between the flange 1% and the endsurface of the cylinder 12. The thickness of the cylinder wall 12 ispredetermined in accordance with the operating pressures used, theservice contemplated, the amount of metering resorted to in the use ofthe metering tube, and associated ducts connecting the tube with thereservoir. It is obvious that the expanding cylinder wall for meteringliquids may be used in combination with other metering media in avariety of ways. For example, the expanding wall of FIG. 5 may be usedas the principal metering medium for discharging liquid from thecylinder to the reservoir in combination with a check valve associatedwith the metering tube to open only when liquid flows from the reservoirinto the cylinder during a return stroke.

The terms and expressions which have been employed are used as terms ofdescription and not of limitation and there is no intention of excludingsuch equivalents of the invention described or of the portions thereofthat fall within the scope of the claims.

What is claimed is:

1. A hydraulic buffer which undergoes lengthwise contraction in responseto loading comprising:

(A) a cylinder having a head substantially enclosing its front end, andan open rear end;

(B) an assembly comprising: a piston reciprocable in said cylinder, anda piston rod for the piston extending rearwardly of said open rear endof said cylinder;

(C) a cylinder extension joining with the cylinder at said open-end andextending in coaxial relation with the rod and the cylinder rearwardlyfrom the cylinder;

(D) said assembly having an elongate opening co-extensive with at leasta portion of said extension;

(E) annular sealing means disposed between the rod and the inner surfaceof the extension carried by the rod lengthwise of the extension in fixedlongitudinal relation with the rod, said means preventing passage offluid from the space adjacent to the forward side of said means toregion adjacent the rear side thereof;

(F) a reservoir connected with said cylinder for the transfer of liquidfrom one to the other;

(G) means for conducting liquid between said space and a liquid storageregion comprising the cylinder and the reservoir;

(H) said rod having duct means extending from an intermediate portion ofthe sealing means spaced between its front and rear ends for receivingany liquid escaping by the portion of the sealing means forwardly of theduct means; and

(I) check-valve means and duct means opening only for passage of liquidfrom said space to said opening.

2. A hydraulic buffer which undergoes lengthwise contraction in responseto loading comprising:

(A) a cylinder having a head substantially enclosing the front end, andan open rear end;

(B) an assembly comprising:

(1) a piston reciprocable in said cylinder, and (2) a piston rod for thepiston extending rearwardly from said open end;

(C) a cylinder extension joining with the cylinder at said open end andextending in coaxial relation with the rod and the cylinder rearwardlyfrom the cylinder;

(D) annular sealing means disposed between the rod and the inner surfaceof the extension and carried lengthwise of the extension by the rod infixed longitudinal relation with the rod, said means preventing passageof fluid from the space adjacent the forward side of said means to aregion adjacent the rearward side thereof;

(E) an elongate metering member fixed to said head and extendingcentrally lengthwise of the cylinder; (F) said assembly having anelongate opening for receiving said member extending lengthwise andinteriorly of said rod from the front face of the piston;

(G) a reservoir connected with the head for the exchange of liquidbetween reservoir and the interior of the cylinder;

(H) duct and check-valve means in said assembly for transferring liquidfrom the elongate opening to said space;

(I) said rod having duct means extending from a portion of the sealingmeans spaced from, and between, the front and rear ends of the sealingmeans to said opening; and

(I) check valve means in said duct means opening only for passage ofliquid from said space to said opening.

3. A hydraulic butter which undergoes lengthwise contraction in responseto loading comprising:

(A) a cylinder having a head substantially enclosing its front end, andan open rear end;

(B) an assembly comprising,

(1) a piston reciprocable in said cylinder, and (2) a piston rod for thepiston extending rearwardly from said open end;

(C) a cylinder extension joining with the cylinder at said open end andextending in coaxial relation with the rod and the cylinder rearwardlyfrom the cylinder;

(D) annular sealing means disposed between the rod and the inner surfaceof the extension in fluid-sealing relation with both the rod and saidinner surface and carried lengthwise of the extension by the rod infixed longitudinai relation with the rod;

(E) a hollow metering tube, open at both ends, fixed to said head, andextending centrally lengthwise of the cylinder;

(F) said assembly having an elongate opening for receiving said tubeextending lengthwise and internally of said rod from the front face ofthe piston;

(G) a reservoir and liquid conducting means for transferring liquidthrough the head between the reservoir and the front open end of thetube;

(H) said assembly having a passageway connecting said opening with saidspace;

(i) check valve means in said passageway opening only for passage ofliquid from said opening to said space;

(I) said sealing means having an aperture along a portion thereofdisposed between and spaced from the front and rear ends of the sealingmeans; and

(K) said rod having duct means connecting said aperture and said openingand check valve means associated with the duct means for passage ofliquid from said aperture into said opening.

4. The buffer of claim 3 comprising:

(A) spring means for returning said assembly to a rearward position froma position disposing the piston forwardly within the cylinder;

(13) said cylinder extension having a smaller diameter than the pistonto render necessary the discharge of liquid from said space during areturn stroke of the assembly;

(C) said passageway and the check valve means associated therewithdefining an orifice smaller than the passageway for metering liquid fromsaid space to said elongate opening.

5. The buffer of claim 3 wherein:

(A) said piston defines said passageway and said passageway also opensinto the cylinder along the front face of the piston;

I (B) the piston carries second check valve means in.

(D) said passageway and the'first named check valve means defines anorifice smaller than the passageway for metering liquid opening. a. 6.The hydraulic buffer of claim 3 wherein:

from said space to said elongate (A) said cylinder is resilientlyexpandable under internal hydraulic pressure to develop a liquidtransmitting clearance between a lateral wall portionand said head fordischarging a controllediquantity of liquid from the cylinder. into saidreservoir, 7. A hydraulic buffer which undergoes lengthwise contractionin response toloading comprising:

(A) a cylinder having an end wall; i (B) a piston reciprocable in saidcylinder; and (C) a reservoir for liquid adjacentthe end wall; saidcylinder being expandable relative to the endwall gra ns under internalhydraulic pressure enabling passage of liquid'from the cylinder to thereservoir. 8. A hydraulic bufler which, undergoes lengthwise contractionin response to loading. comprising:

(A) a cylinder having antopenrear end and substantially enclosing itsfront end; (B) an assembly comprising: 7

(1) piston reciprocable in saidvcylinder, and

a head:-

(2) a piston rodfor the piston extending rearwardly of said opencylinder end;

(C) a cylinder extension joining with the cylinder at said open end andextending in coaxial relation with the rod and the cylinder rearwardlyfrom the,cylinder; j v (D) annular means disposed between'the outersurface of the rod and .the inner surface of the extension in' fluidsealing relation with both the rod and said inner surface for sealing aspace forwardly of the annular 45 v. v c

transfer of means with respect to a region rearwardly thereof; (E) areservoir and liquid metering means connecting the reservoir with saidcylinder for the liquid from one to the other; (F) means for conductingliquid between said space v 'and a liquid 'storageregion comprising thecylinder .and the reservoiriand p v I I (G) a cylindrical wall portionof the cylinderbeing expansible with respect. to, said head to provide aclearance for metering liquid fromthe cylinder into said reservoir; I a95 1a a hydraulic. buffer construction including a housing having acylinderand a piston operative therein with a piston-rod projectingsubstantially beyond one end of the ho'using: V i V a (A) a cylinderextension about a substantial portion ofthe piston 'rod in spaced.relation and defining a return stroke, buflerchamber back of the piston;(B) an elongated metering member fixedly concentric Within the cylinder;

(C) thepiston rod having a bore therein opening through the piston andaccommodating, said metering member for metering hydraulic fluid fromthe a cylinder in .front of the piston into said bore;

(D) means for metering hydraulic fluid from said bore into said bufferchamber backof'the piston during a pressure working stroke of the pistonand pistonrod inthe cylinder and cylinder extension; 7

('13) means restraining return of hydraulic fluid from said bufferchamber during return strokes of the piston and piston-rod so vas.toafford return stroke rer sistance pressure to the piston;

.(F) a bearing on, and moving with, the piston-rod spaced from the backof the piston and engaging slidably. in the cylinder extension andproviding a closure'jfor said butterchamber;

(G) sealing means on the piston-rod associated with the 'outer'end ofthe bearingto prevent escape of V hydraulic fluidthat may leak past thebearing due to said return stroke resistance pressure;

(H)qa pressure relief passageway from the sealing means through thevpiston rod into said bore for draining the hydraulic fluid leakage fromsaid sealing means during return'strokes of the piston and pistonrod;and i i V (I) check valve means in said pressure relief passagewayclosing the passageway during pressure working strokes of the piston andpiston-rod and opening the passageway during return strokes to thepiston and piston-rod Noreferences cited. ARTHUR L. LA POINT, PrimaryExaminer.

1. A HYDRAULIC BUFFER WHICH UNDERGOES LENGTHWISE CONTRACTION IN RESPONSETO LOADING COMPRISING: (A) A CYLINDER HAVING A HEAD SUBSTANTIALLYENCLOSING ITS FRONT END, AND AN OPEN REAR END; (B) AN ASSEMBLYCOMPRISING: A PISTON RECIPROCABLE IN SAID CYLINDER, AND A PISTON ROD FORTHE PISTON EXTENDING REARWARDLY OF SAID OPEN REAR END OF SAID CYLINDER;(C) A CYLINDER EXTENSION JOINING WITH THE CYLINDER AT SAID OPEN-END ANDEXTENDING IN COAXIAL RELATION WITH THE ROD AND THE CYLINDER REARWARDLYFROM THE CYLINDER; (D) SAID ASSEMBLY HAVING AN ELONGATE OPENINGCO-EXTENSIVE WITH AT LEAST A PORTION OF SAID EXTENSION; (E) ANNULARSEALING MEANS DISPOSED BETWEEN THE ROD AND THE INNER SURFACE OF THEEXTENSION CARRIED BY THE ROD LENGTHWISE OF THE EXTENSION IN FIXEDLONGIDTUDINAL RELATION WITH THE ROD, SAID MEANS PREVENTING PASSAGE OFFLUID FROM THE SPACE ADJACENT TO THUE FORWARD SIDE OF SAID MEANS TOREGION ADJACENT THE REAR SIDE THEREOF; (F) A RESERVOIR CONNECTED WITHSAID CYLINDER FOR THE TRANSFER OF LIQUID FROM ONE TO THE OTHER; (G)MEANS FOR CONDUCTING LIQUID BETWEEN SAID SPACE AND A LIQUID STORAGEREGION COMPRISING THE CYLINDER AND THE RESERVOIR; (H) SAID ROD HAVINGDUCT MEANS EXTENDING FROM AN INTERMEDIATE PORTION OF THE SEALING MEANSSPACED BETWEEN ITS FRONT AND REAR ENDS FOR RECEIVING ANY LIQUID ESCAPINGBY THE PORTION OF THE SEALING MEANS FORWARDLY OF THE DUCT MEANS; AND (I)CHECK-VALVE MEANS AND DUCT MEANS OPENING ONLY FOR PASSAGE OF LIQUID FROMSAID SPACE TO SAID OPENING.